Vulnerable girls as young as 11 were groomed, subjected to acts of "extreme depravity" and trafficked around the UK for sex by a gang of men based in Oxford, a court has heard .

Over a period of eight years the nine men made the girls' lives a "living hell", subjecting them to extreme physical and sexual violence, selling some victims for prostitution in Oxford and trafficking others around the country, an Old Bailey jury was told.

It took more than half an hour to read out the 51 counts against the men, who sat impassively in the dock, accused of crimes including rape, forcing a child into prostitution and trafficking.

The jury of seven men and five women heard that from 2004 to early 2012 six complainants were plied with drugs and drink, and raped, sometimes by several men and sometimes "for days on end".

The men targeted children in care or from chaotic backgrounds, the jury heard. Once groomed, the girls could then be used to recruit other children into the sex ring. Some of the girls, ranging in age from 11 to 15, were groomed to be child prostitutes, for which some men in the gang received payments.

The nine face 19 counts of rape, seven of them with a child aged under 13. Other counts include arranging or facilitating child prostitution, trafficking within the UK for sexual exploitation and using an instrument to procure a miscarriage.

Noel Lucas QC, prosecuting said: "The depravity of what was done to the complainants was extreme."

He told the jury that they would have to steel themselves to hear the evidence. "The facts in this case will make you feel uncomfortable. Much of what the girls were forced to endure was perverted in the extreme."

The children were taken to guest houses and empty houses, thought to be kept for the abuse, and prevented from escaping.

They were subjected to "humiliating and degrading conduct", including biting, suffocation, burning and scratching. Weapons, including knives, baseball bats, knives and meat cleavers were used during the torture, the court heard.

The jury was told that sometimes men had urinated on the girls, who were raped vaginally, orally and anally.

The children were groomed in a variety of ways, given gifts or "simply shown the care and attention they very much craved", said Lucas.

"The attention lavished on the girls at the outset was of course entirely insincere, as it was merely a device, you may conclude once you hear the evidence, to exploit their vulnerability," he said.

He said the girls were also given "so many drugs they were barely aware of what was going on – indeed they say it was the only way they could cope with what was going on".

The men gave the girls cannabis, cocaine, crack and sometimes heroin.

"The girls became addicted to certain of the drugs and felt unable to live without them. This made them even more dependent on the men," he said.

The men, who were arrested by Thames Valley police as part of Operation Bullfinch, controlled the girls in their power entirely.

They were threatened "that should they ever seek to free themselves from the grasp of the group they and their families would suffer serious harm".

The men targeted girls who were unlikely to be believed and whose behaviour would be seen as delinquent, said Lucas. It was, according to one of the girls "a living hell" from which there was no escape.

The gang took some of the girls to empty houses where other men from as far away as Bradford, Leeds, London and Slough, would "come by appointment" to pay to have sex with them, Lucas said.

On other occasions girls were ferried to London and Bournemouth.

In his opening statement, Lucas told the court that one girl, who can not be named for legal reasons, was 12 when she was targeted by the gang while playing truant from school.

She was subjected to extreme physical, sexual and psychological abuse until shortly after her 15th birthday. The jury heard that she was in contact with police twice in 2006, and they would see a video interview carried by police in September of that year. Her abuse only came to an end when she "decided it all had to stop" and she threw her telephone away and went back to school, said Lucas.

The court heard that as part of the grooming process, the alleged victim, called Girl A, who had been put into care, introduced another teenage girl to the gang. In September 2006 the girls absconded from the home, returning two days later in a taxi. The jury heard that Girl A said she asked the children's home to pay the fare, but when they refused the girls returned to their abusers in Oxford.